Mutation detection

The next step in mutation breeding is to detect which plants have indeed produced the desired new traits. With recent breakthroughs in detection technologies we help Member States screen plants more efficiently and speed up the development of mutant lines for commercial use.

The detection of novel induced mutations in plant mutation breeding has long been a major challenge. Mutation events occur in such low frequencies that the detection of useful mutations requires the creation of very large mutant populations. The production, handling and assaying (analysing) of mutant populations with often many thousands of individual plants is a large undertaking. It is often considered the real “art” of mutation breeding to identify and select among the many mutated plants those rare cases that have developed a new desirable character as result of the mutation.

Jointly with the FAO, the IAEA strengthens Member States’ capacities to increase the efficiency of the required screening methods and to accelerate thereby the development of mutant lines of crops into commercial varieties usable by farmers.

The process of identifying and selecting mutant plants with improved traits involves two major steps: mutant screening and confirmation (also referred to as mutant validation). Since plants were first domesticated, screening by visible characteristics (phenotypes) has been the most common method in plant breeding to select improved crops. Screening protocols, such as for salt tolerance in hydroponics (a method of growing plants using mineral nutrient solutions without soil), drought tolerance screening methods or disease screening protocols, are efficient methods for mutant phenotyping detection.

One such tool is genotype screening, with which differences in the genetic make-up (genotype) of individual plants can be determined by examining an individual's DNA sequence using biological assays (a type of scientific experiment), and comparing it to another individual's sequence or a reference sequence. With this tool, a variation can be identified that is linked to and inherited with the trait of interest.

Recent breakthroughs in high-throughput mutation detection technologies, such as whole genome sequencing, have increased the efficiency of identifying the DNA changes that generate a new trait. With this, molecular markers could be developed that help the breeder speed up the process of incorporating the desired trait into other commercial varieties. Other efficient high-throughput methods for screening induced DNA deletions include reverse genetic techniques, such as TILLING (Targeting Induced Local Lesions in Genomes), which allows directed identification of mutations in a specific gene.